This invention relates to a method of and an apparatus for printing patient information on an X-ray film carried in an X-ray cassette. More particularly, the invention relates to computer controlled systems for collecting and printing patient identifying and X-ray machine identifying information on X-ray film and storing the same for archival purposes and to ensure the integrity of such information.
Many X-rays, such as mammographic X-rays of breasts, are performed on an X-ray machine that uses an X-ray film holder called a cassette that slides into and out of a support on the X-ray machine. The typical cassette is a rectangular flat package that is hinged at one end to open to allow access to an internal foam pad on which is laid an X-ray film sheet that will receive the X-ray image. Currently, most such cassettes also have a narrow window slide in one corner of the cassette that is slid open to expose the film for printing patient data through the window onto the film.
Typically, the patient data of interest includes identity, time and location information and the X-ray machine data of interest includes the type of view, the operating parameters and other information relating to the X-ray machine. For a mammogram X-ray, it may be desired to set forth in four to six rows of information: the clinic name, date, time, patient name and identification number, exposure number, voltage used, exposure time, mode, technique used, angle of C-arm, breast thickness, compression force, filter and dosage. The letters to be printed are about newspaper size lettering; and the letters need to be nice, crisp and clear. The letters are white on an exposed, black background and may have to be printed in a space that is only 0.5 inch in height and 2.5 inches in length.
Currently, X-ray film is being marked by systems in which the information is furnished on data carrier cards and liquid crystal displays (LCDs) which are illuminated to project the information onto the film. Such systems have been designed to use data carrier cards or liquid crystal displays or some combination thereof.
A system employing data carrier cards provides a label printed with the desired information and attached to an IBM perforation card which is placed into an exposure unit along with the X-ray cassette. An electrically operated finger slides the cassette window slide to an open position to provide the window through which light is flashed to expose the letters on the film. The slide is then closed and the cassette is removed from the exposure unit, as is the IBM card bearing the information label thereon.
Since it sometimes occurs that cassettes and IBM cards are inadvertently mixed such that the film is marked with incorrect information, it has been found desirable to provide an indication of precise date and time information with the exposure. Previously, a timer disk driven by a motor has been mounted adjacent the data carrier card to project such information. However, such timer disks are bulky and the information provided thereby is often highly inaccurately and cannot be readily deciphered by a physician. To this end, U.S. Pat. No. 4,383,329 to Krobel et al. entitled "Apparatus for Recording Data on X-ray Films or the Like," issued May 10, 1983, proposed providing a liquid crystal-type digital clock display including a digital calendar and counter adapted for use in an exposure unit to mark film with such information. By proposing both a data carrier card and a liquid crystal display, Krobel et al. would provide marking of patient and X-ray machine identification information, along with time information.
The separate act of providing a label with the desired information and attaching it to an IBM card and then positioning the card in the exposure unit results in a system which is slow and expensive. U.S. Pat. No. 5,136,626 to Ort, entitled "Method for Identifying X-ray Film with Patient Information Displayed Outside a Cassette," issued Aug. 4, 1992, proposed adding a liquid crystal display as an integral component to a cassette to perform the function of the data carrier card. The Ort cassette has a number of control contacts allowing information to be transferred to the display from a data processing unit having a user keyboard for entry of such information.
Today, information which might be found useful for marking on X-ray film is available from a wide variety of data sources. Such sources include computers which might reside in the medical setting, including main frames in personal computers, and also some X-ray machines which provide for a digital interface allowing access to machine data. Prior art exposure units, however, are designed to receive information provided by a human operator, requiring that the operator transcribe all such information, which is tedious and subject to human error. It would be desirable, therefore, to take advantage of the various data sources available by retrieving data directly from the source, whether it be an interface computer, an X-ray machine or both. Thus, there exists a need for a new and improved system for marking patient and X-ray machine identifying information on X-ray films in cassettes.
Preferably, an improved marking system should include an exposure unit which is easy to use, both as a stand-alone unit and with remote apparatus interfaced thereto. It would therefore be further desirable to provide a "smart" marking system which itself includes a computer or microprocessor, facilitating efficient retrieval of information from the various data sources. Rather than merely receiving information, a smart marking system could directly retrieve information from data sources. As such, a smart marking system might include various interface ports, allowing the system to interrogate for the presence or absence of information sought for marking. Establishing a hierarchy of data sources as inputs would allow for the automatic and/or semi-automatic operation of the smart system to optionally look for patient and X-ray machine information from the computer interface, the X-ray machine interface or the user keyboard in the absence of data from computer or machine interfaces.
Under new regulations, the X-ray data and the patient identification data must be printed on the X-ray film prior to removal of the X-ray film from the cassette. A large number of mammography and chest X-ray machines exist today and are in use without having any way of printing such information on the X-ray film. The present invention is directed to solving this problem by providing a stand-alone apparatus that can be used, for example, in a clinic in connection with one or several mammography machines that have no computer output capability. In order to be effective, the flasher apparatus has to be low-cost in comparison to the mammography machines which typically cost about $60,000 to $80,000. Preferably, the flasher apparatus should cost less than a tenth of this cost range. In addition to being cost effective, the flasher apparatus must be relatively foolproof; and yet, simple to operate, and fast in operation. That is, the apparatus should check that cassette is properly positioned and that window slide is fully opened before a flashing operation is done. Also, to prevent a repeated erroneous operation, it is desired that the flasher flash patient information only once and not be capable of repeating an erroneous flash of a patient's data onto a succeeding cassette of another, subsequent patient. The preferred apparatus should be capable of operating the three modes of manual only; semi-automatic with some information coming from a remote computer such as patient data from a hospital main frame and X-ray parameter data generated by the keyboard; and fully automatic with all of the information coming from a computer associated with the mammography machine.